Ever since installing a new ADSL Modem/Router last week the Check for Updates feature of DOpus has ceased to function returning an "Unable to Resolve Host Name" error. (an NSLookup in a command box resolves the address just fine).
Does the update feature require a particular port opening on the Router in order to function? If so, Which? No problems were experienced on the old router.
As far as I know the update check is done over HTTP port 80, and only uses outgoing connections, so it should be no different to a web browser requesting a web page.
Does your web browser need to use a proxy with the new router?
No. No proxy. The fact that I can successfully do both an NSLookup and a ping on the specified URL is also suspicious in itself in that it proves DNS is working correctly and, therefore, suggests that the URL quoted in the error message is not, perhaps, the url that the update process is trying to access (www.gpsoft.com.au).
My system is running Kaspersky Internet Security, but with the Firewall component disabled as firewall services are provided by the router, and I see no advantage in running two firewalls.
I just activated Kaspersky's firewall and ran the DO updater .. and it worked. Disabling the Firewall again and subsequent attempts to update also work. It seems that, for some reason, at least one attempt to update needed to be made with the second firewall active after which it is not needed.
I don't understand why this is happening, but at least it now works. Thanks VM for your help.